Update flask requirement from <2.3,>=2 to >=2,<3.1

Updates the requirements on [flask](https://github.com/pallets/flask) to permit the latest version.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](pallets/flask@2.0.0...3.0.0)

---
updated-dependencies:
- dependency-name: flask
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

pyproject.toml

@@ -39,7 +39,7 @@ dependencies = [
     "Flask-Talisman>=0.8,<2",
     "Flask-WTF>=0.14.3,<2",
     "WTForms>=2.3.1,<3.2",
-    "Flask>=2,<2.3",
+    "Flask>=2,<3.1",
     "Werkzeug>=2,<2.3",
     "itsdangerous>=2,<3",
     "Jinja2>=3,<4",